DevDocs : DevDocs combines multiple API documentations in a fast, organized, and searchable interface.
API Security Checklist : Checklist of the most important security countermeasures when designing, testing, and releasing your API.
WebPlatform.org : Web Platform Docs is a community-driven site that aims to become a comprehensive and authoritative source for web developer documentation.
Swagger : Swagger is a powerful open source framework backed by a large ecosystem of tools that helps you design, build, document, and consume your RESTful APIs...
This guide describes a set of HTTP+JSON API design practices, originally extracted from work on the Heroku Platform API.